Computer Hardware: Binary, Bus Speed, Memory, and More
Binary to Decimal Conversion
Binary/Decimal:
- List the powers of 2 from right to left, starting with #1. Increment the exponent by 1 for each power. Stop when the amount of elements in the list is equal to the amount of digits in the binary number.
- Only if the digit is a 1, write down its corresponding power of 2.
- Finally, add all the numbers to get the answer.
Bus Speed and Width
Bus Speed: The number of bits or bytes that the bus sends in a unit of time (a second is the most common). For example, a 100 Mbps computer sends 100 megabits of data in a second.
Bus Width: The size of the data that the bus sends in 1 cycle. For example, a 32-bit computer has 32 wires that are used for the transmission.
Memory: DRAM and SRAM
DRAM (Dynamic Random-Access Memory): A memory chip that is used as main memory. DRAM must be constantly refreshed with pulses of electricity to maintain the data stored in the chip.
SRAM (Static Random-Access Memory): A memory chip that is used as cache memory. SRAM is much faster than DRAM and does not have to be refreshed as often.
Parity and Error Correction
Non-Parity: It can’t detect corrupted data, so if there is some, it can’t fix it.
Parity: Contains 8 bits for data and 1 bit for error checking: the parity bit. 99% of the time we’re working with odd parity. This means that the byte of data, including the parity bit, should be odd (impar). This way, this system can detect data corruption. If the output is even (par), then we’ve corrupted data. In the case of multiple errors, this system can’t detect them.
Error Correction Code (ECC): Error checking & correction (technology) or error correction code (software). It uses logarithms to detect if data is corrupted or not. It can also correct the error, but not multiple errors. ECC is not faster than parity, but it is more reliable.
Expansion Buses: PCI, AGP, and PCIe
PCI (Peripheral Component Interconnect): There are 2 levels of voltage signal. It is keyed for different voltages. This allows you to know the voltage level depending on the key given. This also happens when, depending on the size, you can know if it’s a 32 or a 64-bit store.
AGP (Accelerated Graphics Port): It is a bus used for connecting peripheral devices to the computer motherboard. AGP buses operate at different frequencies and voltages, and there are more differences between them than in the case of PCI. It was produced as a solution to the bottleneck that occurred in graphics cards when using the PCI bus. The AGP bus is only used to connect graphic cards.
PCIe (Peripheral Component Interconnect Express): It is much faster than the 2 previous buses. It doesn’t use the buses; it uses lanes (unidirectional serial) instead. Each expansion slot takes 1, 2, 4, 8, 16, or 32 data links between the motherboard and the connected cards, expressed as x1, x2, x4, x8, x16 & x32. Both of them control the data between all the components and the microprocessor.
Northbridge and Southbridge
Northbridge: Is connected directly to the microprocessor. It controls the data between all the components and the microprocessor. It is very fast, so all high-speed components are connected to it. Also, the AGP port is connected directly to the north bridge, because it has to be as close to the RAM as possible. It is the same for the PCI express. It is close to the fan and it contains a heat sink, as its temperature tends to increase. It is used for video-cards.
Southbridge: In contrast to the northbridge, it is slower and it doesn’t get as hot as it. The southbridge incorporates a number of different controller functions. It supervises data transfer to & from the hard disk. It is located close to the PCI slots and it is used to connect peripheral devices such as LAN card, sound card, modem, network & firewire…